1. Technical Field of the Invention
The present invention relates in general to the field of communications, and in particular, by way of example but not limitation, to network node selection that adapts to network conditions.
2. Description of Related Art
When a user of the Internet today begins looking for a web site, he or she specifies a symbolic name such as xe2x80x9cwww.my.isp.comxe2x80x9d. However, the computer and the underlying protocols used to connect the user to this web site do not understand symbolic names, for they only understand Internet Protocol (IP) addresses, i.e. logical names. Consequently, some mechanism is needed to convert the human-understandable symbolic name to a computer-understandable logical name such as an IP address of a web server. This method of mapping symbolic names to logical names using a, e.g., distributed database is known as the Domain Name System (DNS).
The DNS is currently used in, for example, General Packet Radio Service (GPRS) and so-called Third Generation (3G) networks. For simplicity, the GPRS network shall be relied on for examples and illustration purposes. In a GPRS network, there are Serving GPRS Support Nodes (SGSNs) and Gateway GPRS support nodes (GGSNs). The SGSNs are connected to the GGSNs through what is known as the Gn interface/network, and each of the GGSNs are connected to an external Packet Data Network (PDN) (e.g., Internet Service Provider (ISP), corporate network, etc.) through what is known as the Gi interface/network.
The DNS is used in GPRS networks as follows: When a mobile station (MS) user attaches to the GPRS network, he or she typically specifies what is known as the Access Point Name (APN), which is used to specify the external PDN to which the MS wishes to connect. The APN links a name to a list of possible GGSN IP addresses that are connected to the external PDN that the MS specified in its PDP Context Activation.
The SGSN queries the DNS Server for a mapping of the APN (typically specified by the MS) to GGSN IP addresses. The DNS server responds to the DNS query by returning a list of possible GGSN IP addresses. The SGSN then xe2x80x9cchoosesxe2x80x9d the first IP address in the list and attempts to establish a GTP tunnel/session with this GGSN via the Gn interface/network, and then the GGSN connects the MS to the external PDN requested via the Gi interface/network.
If the SGSN is unsuccessful in establishing a GTP tunnel/session with the first GGSN in the list, it traverses the list it received from the DNS server by attempting to establish a GTP Tunnel with the next GGSN in the list. This procedure is repeated until the SGSN successfully establishes a GTP Tunnel with a GGSN or until the list is exhausted, i.e., the end of the list is reached.
The prior art is improved by the methods, systems, and arrangements of the present invention. For example, as heretofore unrecognized, it would be beneficial to update a nomenclature-network address selection response based on current network conditions. In fact, it would be beneficial if addresses and/or routings were provided to requesters only if related network elements were thought to be available.
Methods, systems and arrangements enable a node selector (e.g., an adaptive domain name server (DNS)) to monitor the network to facilitate routing to/through network nodes and over network links that are functioning and/or that are geographically/location efficient. Such an adaptive node selector may include a nomenclature-nodal address mapper and/or filtering data structure in which one or more fields and/or filters indicate whether network node(s) and/or network link(s) (e.g., as representable by key IP addresses) used to route through and/or to the node of the mapped nodal address is/are available/up.
In certain embodiments(s), the monitoring may be effectuated by polling (polling via, SNMP and/or ICMP) the network and acting according to what is ascertained from the results of monitoring the, e.g., key IP addresses in the network. Monitoring may also be achieved by keeping state of the network through the use of Dynamic Routing Protocols such as RIP, OSPF and BGP and acting accordingly to what is monitored.
In certain embodiment(s), the adaptive node selector may also include a filter. More specifically, an adaptive node selector filter may be based on any one or more of different criteria. For example, the criteria may be based on the source of the query, a given fixed number of addresses to return, etc. Also, the adaptive node selector may group addresses based on different nodal criteria such as geographical location, functionality, or capacity.
In certain embodiment(s), the network may be a general packet radio service (GPRS) and/or 3G network, while (i) the network nodes may be Serving GPRS Support Nodes (SGSNs) and Gateway GPRS Support Nodes (GGSNs) and (ii) the network links may be Gn and Gi links, of which key IP addresses on these links may be monitored to ascertain if the connection to the network through these links is available/up or unavailable/down.
The above-described and other features of the present invention are explained in detail hereinafter with reference to the illustrative examples shown in the accompanying drawings. Those skilled in the art will appreciate that the described embodiments are provided for purposes of illustration and understanding and that numerous equivalent embodiments are contemplated herein.